The present invention relates to a shutter for a single lens reflex camera and more particularly to a shutter which performs an exposure operation by actuating a shutter blade by means of a drive motor.
A shutter in which the opening and closing actuation of a shutter blade is performed by a drive motor is composed so that the motor is rotated forwardly by a release operation thereby to open the shutter blade gradually, and the motor is rotated reversely when the opening quantity reaches a value corresponding to the brightness of the object so as to close the shutter blade.
When such a shutter is applied to a single lens reflex camera, the shutter blade must be kept opened for determining the composition of the object and then closed once when the photographing action is commenced. However, the closing movement of the shutter blade follows actuation of to the motor, and in a motor which rotates slowly, a time lag is produced until the exposure operation is completed, and a discrepancy results between the exposure value intended by a photographer and that of the photographed scene.
In order to solve such a problem, it is required to increase the motor speed, but there are such problems that consumption of the camera battery is large because the consumption current of the motor is increased, the motor size becomes larger and so forth, which are not suitable for a portable camera.